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How to Install Fiberglass Insulation in Your Attic

By: Joe Truini

When installing fiberglass insulation in your home, be sure to put the paper or foil vapor barrier facing toward the heated and cooled living area of the home (down in attics, up under floors, in on walls) to prevent condensation from occurring.

If you are applying an additional layer of fiberglass insulation to your attic, use unfaced insulation on top of the existing insulation to keep from trapping moisture between the layers.

13 Comments on “How to Install Fiberglass Insulation in Your Attic”

I only have four inches of insulation in my attic. I am going to put a four foot runway of boards down the middle of the attic so I have a way of getting around. If I add at least 8 inches more of roll or blown insulation how do I put insulation over the boards so I have access later to the attic?

Rolled insulation is fine to use, just make sure you get “UNFACED” insulation. In other words, get the rolls that have no paper backing on them. I would also roll it out so it is perpendicular to the existing ceiling joists.

Hi Adam,
When your attic doesn’t have any insulation, place the facing down toward the living space. In mild climates a vapor barrier isn’t necessary, while in colder climates it is to prevent condensation from forming in the insulation during the winter.

Hi Kate, It’s not necessary to insulate attic walls because it’s an unheated space. The idea is to keep the temperature inside the attic as close as possible to the outside air temperature. It makes much more sense–and cents–to insulate the attic floor, which in effective is insulating the ceiling of the rooms below. That way, you block heated air (and air-conditioned air) from escaping through the ceilings and leaking into the attic. Hope this helps. Good luck!–Joe T.

Hi Cheryl,
The paper facing on insulation has an asphalt layer which acts as a vapor barrier. You only want one vapor barrier in your attic, and it should be as close to the ceiling as possible to prevent warm, moist air from coming up from the heated house and condensing when it hits the cold air in the attic. So if you’re installing insulation in an attic that doesn’t have any, used faced insulation and put the paper side down toward the ceiling. If you’re installing additional insulation in an attic that’s already insulated, use unfaced insulation that doesn’t have a vapor barrier. You can find out more in our articles on How to Apply a Vapor Barrier to Attic Insulation and Which Way to Face Insulation. Hope that helps!

This whole insulation installation is very, very confusing. The video above shows that the fluffy side of the insulation is facing up. When the recommendation is to put the fluffy side down with the paper part facing the ceiling. So why did this guy in the video have the paper side down towards the floor and the fluffy side up. Don’t forget we are homeowners who needs to understand in layman terms. Show us and tell us as if we have no common sense, because we don’t.

I just seal coated my driveway. I used a broom like bristle brush. It dried and you can see the streaks. From a distance it looks great. Question? Can I use a paint roller attached to a long handle and go over the driveway again to remove the brush streaking?? Will it work?
Thanks. Paul

i have 12″ of insulation in the attic, problem where a contractor put in the stove vent the snow has been melting, i added some insulation but this problem is still there, i could not get to the suffit area to put insulation on top of the pipe and i i did i would be blocking off any venting from there, actually the area they put the outside vent at that location is blocked, can i stuff that 1 section with insulation? i never noticed this until i moved upstairs in the garage and been like this for a long time.
thanks mike

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